Cryotherapy modulates femoral nerve afferent signals after simulated anterior cruciate ligament reconstruction in a rabbit model.

BackgroundAberrant sensory information arising from damaged knee joint tissues is an underlying cause of post-traumatic quadriceps arthrogenic muscle inhibition which commonly follows joint injury. This study aimed to determine if aberrant sensory information from damaged knee joints could be modulated using cryotherapy.MethodsComposite femoral nerve sensory signal was measured during passive knee extension in 16 rabbits. Ten rabbits underwent unilateral leg surgery to simulate the joint damage created during anterior cruciate ligament reconstruction, and 6 rabbits were healthy controls receiving no intervention. Focal knee joint cryotherapy treatment was administered for 15 minutes in all 12 control and 10 surgical limbs. Nerve measurements were repeated after cryotherapy. Side-to-side ratios (surgical side vs. contralateral healthy side) for peak filtered and integrated whole nerve composite signal were compared before and following cryotherapy treatment.ResultsPeak femoral nerve signal was significantly higher in the surgical leg (4.68±1.95) compared to the contralateral leg (3.25±2.04) in rabbits who underwent unilateral surgery (p=0.049). There was no difference in side-to-side limb comparison in control animals (p=0.337). The peak femoral nerve signal in the surgically involved rabbits was significantly reduced following cryotherapy in the surgical leg (p=0.005).ConclusionComposite femoral nerve afferent signal is greater in injured knees than in healthy knees relative to the contralateral side. Cryotherapy resulted in a significantly downregulated sensory response from the surgical limb.